I am describing the final lens, that I have got after my bumpy ride with Nikkor 18-55mm f3.5-5.6 and other kit lenses. I bought it in January and I am very happy with it.
The Sigma 18-35mm f1.8 Art is not a kit lens, although can be used on a day-to-day basis. The lens is quite heavy (810 g). Initially I was going to have 2 sigma lenses: Sigma 17-70 f2.8 – 4.5 Macro as a kit lens and Sigma 18-35mm for ocassional night photography and stargazing. I conceived that Sigma 17-70 f2.8-4.0 is fine, but frankly speaking this lens can be replaced by Sigma 18-35mm for someone, who already have a zoom range from 55mm (in Nikkor 55-300mm f3.5 – 5.6) and quite good macro is not highly demand. I decided to own only one from these two: Sigma 18-35mm, at least from the time being. I bought this lens brand new to avoid next disappointments, that I experienced with previous orders.

The Sigma 18-35mm is the best lens, which I actually have and the most expensive one. I would like to show all its features below. First of all this lens is simply extraordinary. If you don’t mind the weight the Sigma 18-35mm f1.8 will be a fantastic choice for you. The lens has a lot of pros, where the most important is ultrasharpness at every setting. Moreover this lens is wide-open with silent focus. Basic cons of this lens is his size (is big and heavy) and a silly zoom range.

Construction & Design & Performance

The construction of the lens is very solid and much better than standard kit lens. This is the first zoom lens in history with constant f/1.8 aperture. The lens has a plastic shell with a mixture of metallic parts. The optical elements has been made with high-grade glass. One downside in the lens construction is lack of the rubber gasket on the mount to prevent dust and other debris from getting into camera. The handling with lens is comfortable as long as you are comfortable with a reverse rotation on focus ring. A very important thing is, that both zoom and sharpness are marked (Pic. 2). This is very useful during the low light conditions and stargazing, when you must use the manual focus.

The autofocus is accurate, silent and very fast. Probably partly due to the high brightness, the AF is also accurate in low light. The biggest atitude is internal focusing, meaning that the length of the lens does not change and the filter mount does not rotate while focusing. Also with zooming in or out, the length of the lens remains unchanged. The main exception, that can be noticeable especially in low light conditions is lack of built-in Vibration Reduction (Pic. 3-4).

Even when you set the maximum aperture and taking pictures when dark without tripod you can get the images not sharp enough. Sometimes in the night-time conditions autofocus may not set correctly. It happens especially when some additionals factors occurs (e.g precipitation)(Pic. 5-6).

Pic. 5, 6 The autofocus mismatches during the night-time conditions when snowing. Focus was set on snowfall instead of much brighter buildings beyond. I think, that this issue arises out of the incompability between Sigma and Nikon D5300. 5 – normal, 6 – cropped Cambridge, Mill Road, UK.

Next to the autofocus the manual focus is available at any time by rotating the focus ring (Pic. 9). A clear distance scale runs from the closest focusing distance of 28 cm to infinity. Focus also follows fast action well.

The sharpness at maximum aperture is already very high. This feature differs the Sigma 18-35mm f/1.8 from another bright lenses, which at maximum aperture are usually fuzzier. Comparing to different lenses pretty awesome is also a corner sharpness, however the corners are weaker than the center at all apertures. Having an D5300 DSLR camera I am not a perfect person to describe the autofocus and sharpness features in Sigma 18-35mm f/1.8, because of incompatibilities between this lens and Nikon D5300 camera. The lens may not autofocus correctly in live-view mode and also the Optical Stabilization may not work correctly. I need also avoid some dynamics autofocus settings. Returning to Sigma 18-35mm f/1.8 sharpness in general I would like to say, that the biggest sharp image is with 18mm. For picture with 35mm the sharpness level is the weakest, but the difference is not huge.

The combination of sharpness of the subject and the background blur are sensationally good. In my opinion bokeh delivers very good background blur. This bokeh feature is great for eye-catching portraits and close-up photography.

Pic. 15 Rubus Fruticosus; 35mm, 1/200s, f/10, ISO 400.

Pic. 16 Birch; 35mm, 1/60s f/8, ISO 560.

Pic. 17 Cornus Kousa; 35mm, 1/80s, f/8, ISO 400.

Distortion

The level of distortion in Sigma 18-35mm f/1.8 is moderate. It ranges from light-barrel-shaped at focal length of 18mm to light pincushion-shaped at focal length of 35mm. It means, that at 18mm image magnification will decrease with distance from the optical axis unlike to 24mm and more, where the effect will be opposite. This behaviour is characteristic for a zoom lens with this focal length range. The most optimal focal length to make e.g panoramas is about 22mm.

Pic. 19 Distortion at 20mm appears to be slightly smaller. You can see it on the curb.

Pic. 20 Distortion at 22mm, the most optional for Sigma 18-35mm f/1.8 Art.

Pic. 21 Distortion at 24mm appears to be much bigger than at 22mm.

Pic. 22 Distortion at 35mm is also less visible due to bigger focal length. Corrie Road, Cambridge, UK.

Chromatic Aberration

Chromatic aberration can be detected on some shots, but fortunately is not as much prominent as in another lenses. The biggest chromatic aberration is to be seen at maximum aperture at 24mm. Especially lateral chromatic aberration is clearly visible and needs correction in the lower range of zoom. The chromatic aberration appears as an magenta or blue-green edges at strong contrast transitions in the corners of the image.

Pic. 23, 24 The chromatic aberration in Sigma 18-35mm f/1.8 Art remains almost invisible. Red arrow shows only 1 very faint bright line near to the darker object. I think, that most of people will not spot it, hence I can say, that basically chromatic aberration doeasn’t exist in this Sigma model, 35mm 1/500s, f/11 ISO 220; 23 – normal, 24 – cropped; Bohol Sea, Phillipines.

This is a fatal flaw of the Sigma 18-35mm f/1.8. The very clear and annoying flare patterns are visible both with the light source in frame as well as when the light source is just out of frame. The opinion of users is divided. Some people assert, that only small flare is visible only when doing shots directly towards the Sun or another light source. Another photographers complains. In my personal point of view flare in Sigma 18-35mm f/1.8 is a little bit annoying. When I do photos straight into the Sun both when Sun is inside or outside the frame then I try to cover the beams by my hand. Almost always helps.

When the lens set to its maximum aperture on F1.8, there is significant light fall-off in the corners at both ends of the zoom range. It is noticeable especially in low-light conditions, however remains lower than in Sigma 17-70mm f2.8-4.0 Macro described previously. When set your aperture to F4 the light-fall problem dissapear. In my opinion vignetting is to be more detected at 35mm focal length.

Pic. 29 Vigneting seen in the picture of the Orion constellation presended on light polluted sky in the city centre; 32mm, 1/5s, f/1.8 ISO 12800. Cambridge, UK.

Pic. 30 Vignetting seen in the picture of the cloudy, light polluted sky during the night in the city centre; 18mm, 1s f/1.8, ISO 3200. Coleridge Recreation Ground, Cambridge, UK.

The Sigma 18-35mm f/1.8 DC HSM is not claimed to be a macro lens, but it delivers good performance nonetheless. With minimum focusing distance 28 cm and maximum magnification ratio of 1:4.3 we can do a really detailed close-up shot.

Comparing with another lenses, that I had ocassion to check the Sigma 18-35mm f/1.8 Art macro performs much better than Nikkor 18-105mm f3.5 – 5.6, even better than the kit lens Nikkor 18-55mm f3.5 – 5.6 VR II. I mean the lenses, that doesn’t feature the macro officially, however I am showing the picture below (Pic. 38) as a good comparison between lenses with macro featured.

Pic. 38 The Sigma 18-35mm f/1.8 Art macro quality in relation to Nikkor 18-105mm f/3.5-5.6 and Sigma 24-70mm f/2.8 Macro lenses. The macro has been put from the worst to the best. All examples refers to the Polytrichium Commune moss and they are cropped.

Night photography and stargazing

The Sigma 18-35mm f/1.8 is one of the most nocturnal lenses. Is perfect for shooting star trails, twilight landscapes or anything where every bit of light counts. I am very happy of using this lens for astrophotography purposes. The images are really nice, sharp and full of details in whole focal length range. One thing, that can interrupt your awesome night view is an light fall. This bad feature appears to be seen when shooting for instance cloudy night sky (Pic. 29, 30).

Sigma 18-35mm f/1.8 Art is basically tailored for pictures taking in low light conditions, at least in my opinion. Photographers use this lens for different purposes, like portraits, close-up photography or landscapes. This is undeniably the best lens, which I have. After over 6 months usage I am very happy and I strongly recommend to buy it for everyone, who want to take a beautiful landscape and night sky pictures.